Device for administering an injectable product

ABSTRACT

The invention provides a injection device for administering an injectable product, including a base section adapted to receive a container from which a product dose is dispensed through a needle by displacement of a piston in the container, and a drive unit including a driven member, a drive element and a damping arrangement, the drive unit for applying a force to advance the piston in the container to dispense a dose, wherein the damping arrangement generally counteracts the drive force and counter forces. The invention also encompasses a needle safety sleeve and a blocking structure for use with injection devices.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/554,308, filed on Oct. 30, 2006, which is a continuation of U.S.application Ser. No. 09/902,091, filed on Jul. 10, 2001, now issued asU.S. Pat. No. 7,128,728, which is a continuation of U.S. applicationSer. No. 09/311,434, filed on May 14, 1999, now issued as U.S. Pat. No.6,258,068, issued on Jul. 10, 2001, which claims priority to GermanApplication No. 198 21 933.4, filed on May 15, 1998, the contents ofwhich are incorporated in their entirety by reference herein.

BACKGROUND

The invention relates to devices for administering injectable products,in particular the injection of medically or cosmetically effectiveproducts.

Devices which the invention also concerns are known as injection pens.Generally, an injection pen comprises an elongated, hollow cylindricalhousing in which a container, having the shape of an ampoule, filledwith the product to be administered, is received. An injection needle isattached to the container and when so attached is generally axiallyaligned with or parallel to the central longitudinal axis of thehousing, extending generally from one end of the housing. A drive unitfor a piston within the container is also arranged in the housing. Thepiston is advanced in forward direction within the container under theeffect of a driven member of the drive unit, thus causing apredetermined product dose to be dispensed. For advancing the piston,the driven member itself is advanced in the forward direction (i.e.,toward the needle) in relation to the housing, either manually or by thedrive force of a drive element of the drive unit. In the latter case,energy is stored in the drive unit, which energy is converted into adrive force driving the driven member forward upon the drive unit beingactuated.

In the course of advancement of the driven member, the stored energy orat least part of the same is consumed. The drive force exerted by thedrive element on the driven member is consequently reduced while thedriven member is being advanced. Typically towards the end of theinjection or dispensing cycle, the advancing or forward speed of thedriven member decreases and, therefore, the dispensing rate willdecrease, i.e., dispensing is not uniformly distributed over the totalinjection or dispensing cycle. Other interferences or counter forces maybe caused by irregularities in the internal diameter of the ampoule,resulting in the wall frictional forces affecting the piston, causingnon-constant piston movement over the stroke of the piston and makinguniform dispensing or injection difficult.

SUMMARY

It is an object of the invention to provide for the uniform dispensingor injecting of an injectable product in devices for administering suchproducts.

In one embodiment, the invention is an injection device comprising abase section and a drive unit including a driven member, a drive elementand a damping arrangement. Typically, the base section may accommodate acontainer from which a product dose is dispensed through a needle bydisplacement of a piston in the container. The drive unit applies aforce to advance the piston in the container to dispense a dose, and thedamping arrangement is adapted to generally counteract the drive forceand other counter forces produced during use of the device.

In another embodiment according to the invention, a device foradministering an injectable product comprises a base section, acontainer arranged in or on the base section, from which container aproduct is dispensed through a needle by displacement, in a forwarddirection, of a piston being arranged in the container, and a drive unitcomprising a driven member and a drive element, wherein the driveelement exerts a drive force on the driven member upon the drive unitbeing actuated, thus displacing the driven member in the direction offorward advancement of the piston (toward the needle), thereby advancingthe piston within the container. The drive force may be exerted on thedriven member by a spring, but also by a pressurized fluid, such ascompressed air. For actuation of the drive unit, a blocking means,preventing advancement of the driven member, is released. Preferably, insome embodiments, the drive force is not exerted on the driven memberbefore the release of the blocking means. According to the invention,the device comprises means for generating a controlled damping force,counteracting said drive force in the course of the piston beingadvanced, in addition to unavoidable counter forces. The unavoidablecounter forces essentially are frictional forces acting on the pistonwhen the piston is advanced and any forces generated by the work ofdisplacement the piston performs. Since in addition to these unavoidablecounter forces a damping force is generated which counters the driveforce, the force difference acting on the driven member and resultingfrom the drive force, the unavoidable counter forces and the dampingforce can be controlled much more accurately than is the case in priorart devices.

The damping force is advantageously set to ensure that the product isadministered with the most constant dispensing rate possible. In mostapplications, the dispensing rate is constant upon the piston beingadvanced at constant speed. Accordingly, the damping force in oneembodiment is generated relative to or dependent on the advancing speedof the piston, preferably directly dependent on the advancing speed ofthe driven member. An acceleration increases the damping force and adeceleration decreases the damping force. If the advancing speed is keptconstant, the damping force remains constant. Self-regulation isparticularly preferred.

In preferred embodiments, the damping force will be reduced at leastonce during forward movement. Preferably, the damping force cycleexerted over the advance stroke of the piston is adapted to the cycle ofthe drive force exerted by the drive element. When the energy of thedrive element decreases, the damping force decreases.

In one variation, the damping force is generated by the fact that avolume change work must be performed for the advancement of the piston,due to a chamber increasing or decreasing in volume upon the pistonbeing advanced, with pressure compensation in the chamber only takingplace at a delayed rate. This system is self-regulatory since change inspeed brings about a corresponding change in the damping force.

In another variation, the damping force itself is a frictional force.Due to the design of the components being in frictional engagement forthis purpose, the damping force, in this case caused by friction, iscontrolled.

The invention is preferably used in injection devices. However, it isnot limited to this application. In principle, it may be profitably usedin all devices for administering products in which a drive force causesadvancement of a driven member, including such devices wherein the driveforce directly causes movement of the drive member, and/or in which theadvancement of a piston results from the interaction of a drive forcewith unavoidable counter forces which are predetermined within or resultfrom manufacturing tolerances.

Another object of the invention is to improve removal of a needle safetycap typically applied to the needle in injection devices, in which theneedle is surrounded by a needle safety sleeve during transport of thedevice and only projects over or from a front end of the needle safetysleeve during an injection. In prior art devices of this type, inparticular semi-automatic injection devices and fully-automaticinjection devices, so-called auto-injectors, the needle safety sleeve isslotted in order to allow the user to remove the needle safety cap byaccess through the slot. However, this means that the needle is visiblein the transport position of the device and, in particular, wheninserting the needle, thus possibly producing in the user apsychological barrier against insertion of the needle.

The present invention in large part solves this problem by connecting astripper to the device in such a way that the stripper is displaceableagainst the direction of advancement when inserting the needle. Once thestripper has fulfilled its function, i.e. stripped the needle safety capfrom the needle, thus allowing simple, complete removal of the cap fromthe device, the stripper according to the invention does not impedeinjection, although it is still connected to the device, due to thestripper being either shifted into or over the needle safety sleeve whenthe needle is being inserted. The needle then also projects over orbeyond a front end of the stripper. The stripper is provided withengaging means for clamping or gripping the needle safety cap, but whichdo not impede forward movement of the needle in relation to the stripperand the needle safety sleeve after the needle safety cap has beenremoved.

It is another object of the invention to provide a device according tothe invention, which can be safely handled after administration of aproduct, as a uncovered projecting needle poses a safety problem afteradministration of a product dose. This object is addressed by theinvention in that a needle safety sleeve connected to the device,displaceable in and against the direction of needle advancement, isblockable against retraction from a base position in which it surroundsthe needle beyond its tip as a protection. Preferably blocking iseffected by providing a blocking element or, in a solution that ispreferred, by automatic retraction of the inserted needle after orinjection.

An advantage of the present invention is the operational safety isenhanced. In a device according to the invention, particularly in anauto-injection device in which the needle is automatically advanced byadvancement of the container in relation to the base section, thecontainer is advanced against an elastic restoring force, returning thecontainer for replacement into its rear position.

This advantage is based on the knowledge that when the needle safety capcovering the needle is retracted, the container is pulled slightlyforward against said elastic restoring force, followed by rapidly andabruptly bouncing back into its rear position immediately after the caphas been pulled off due to the restoring force. The container canthereby be damaged. Operational safety is not only jeopardized by therisk of damage to the container, but also by any splinters possiblybreaking off from the container which may block an advancement of thecontainer required for inserting the needle. This risk is preventedaccording to the invention by releasably locking or blocking thecontainer in its rear position, i.e., the base position prior toinserting the needle, against unintentional forward movement.

In one preferred variation of this embodiment, the same blocking elementwhich is already used for blocking the displaceable needle safetysleeve, as described above, is also used for blocking the containeragainst forward movement, i.e., the same blocking element may beoptionally used for the two blocking functions described.

The stripper, the blocking of the needle safety sleeve and the blockingof the container may advantageously be used in connection withcontrolled damping, but may also be applied individually and in asuitable combination with each other.

Other objects, features and advantages of the device and method of thepresent invention will become more fully apparent and understood withreference to the following description and appended drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one embodiment of a device according to the presentinvention, and FIGS. 1 a and 1 b, taken from FIG. 1, depict detailsthereof,

FIG. 2 a depicts the stripper shown in FIG. 1 in a rear position,

FIG. 2 b depicts the stripper in a frontal position,

FIG. 3 depicts another embodiment of a device according to theinvention,

FIG. 3 a depicts details of the embodiment shown in FIG. 3,

FIG. 4 a-e depicts an auto-injection embodiment including blocking ofthe needle safety sleeve,

FIG. 5 a-e depicts the auto-injection device in accordance with FIG. 4a-e including blocking of the container,

FIG. 6 a-b depicts the auto-injection device in accordance with FIGS. 4a-e and 5 a-e comprising an alternative release means, and

FIG. 7 a-c depicts an auto-injection device also including blocking ofthe needle safety sleeve.

DETAILED DESCRIPTION

The accompanying Figures and this description depict and describeembodiments of the injection device and method of the present invention,and features and components thereof. With regard to means for fastening,mounting, attaching or connecting the components of the presentinvention to form the device as a whole, unless specifically describedotherwise, such means are intended to encompass conventional fastenerssuch as threaded connectors, snap rings, clamps such as screw clamps andthe like, rivets, toggles, pins and the like. Components may also beconnected by adhesives, glues, welding, ultrasonic welding, and frictionfitting or deformation, if appropriate. Unless specifically otherwisedisclosed or taught, materials for making components of the presentinvention may be selected from appropriate materials such as metal,metallic alloys, natural and manmade fibers, vinyls, plastics and thelike, and appropriate manufacturing or production methods includingcasting, extruding, molding and machining may be used.

Any references to front and back, right and left, top and bottom andupper and lower are intended for convenience of description, not tolimit the present invention or its components to any one positional orspacial orientation.

FIG. 1 is a longitudinal section of an injection pen, comprising anelongated, hollow cylindrical housing as a base section. The housingcomprises a rear housing sleeve 4 being provided with an internal threadin a front section, and a front housing sleeve 7 being provided with anexternal thread in a rear section. The two housing sleeves 4 and 7 arescrewed to each other in the sections of the two threads. A container 1is arranged within the area of the front housing sleeve 7 and filledwith an injectable product, in particular a fluid medicament.

The container 1 is an ampoule, common to such injection pens, includinga piston 2 arranged in the same. By advancing the piston 2 towards anoutlet at a front end of the container 1, a product dose is displacedfrom the container 1. An injection needle N is arranged on the containeroutlet pointing in the direction of advancement of the piston 2. Theneedle N is covered by a needle safety cap 3.

The container 1 is arranged in and centered by a container holder 30.The container holder 30, too, is formed by a sleeve and comprises in afront area three centering tongues 31 for centering the container 1.Further tongues 32 are formed evenly distributed over the circumferenceof the container holder 30 between the centering tongues 31 andprojecting over the front ends of the centering tongues 31. The furthertongues 32 act as stops when pushing back the needle safety sleeve 10.

An intermediate sleeve 20 is arranged in an annular gap between thecontainer holder 30 and the front housing sleeve 7. The rearcircumference of said intermediate sleeve 20 is provided with recessesthrough which the container holder 30 projects. Thereby, the containerholder 30 is connected to the front housing sleeve 7 non-shiftably inrelation to the front housing sleeve 7; in embodiment, the containerholder 30 is screwed to the front housing sleeve 7. In contrast, theintermediate sleeve 20 is displaceable in relation to the front housingsleeve 7 and the container holder 30 after release of a blocking means21, against the forward direction of the piston.

A releasing sleeve 35 is arranged in the rear housing sleeve 4, a frontface of which is in contact with a rear face of the intermediate sleeve20. The releasing sleeve 35 is essentially a hollow cylinder. A pistonrod, extending rearwards from the piston 2, projects through it. Thereleasing sleeve 35 is arranged in the rear housing sleeve 4 andlongitudinally displaceable in either direction. It is driven by arestoring spring 9 into its frontal position, as shown in FIG. 1, inwhich it is positioned flush in contact with a rear face of theintermediate sleeve 20 and a rear flange face of the container 1. A rearface 36 of the releasing sleeve 35 is chamfered outwards from a rearedge of an internal jacket face. When driving the releasing sleeve 35back, said chamfered face 36 releases a drive unit for advancement ofthe piston 2 and dispensing the product.

The drive unit is formed by a driven member 40 and a drive spring actingas a drive element 49, clamped between the driven member 40 and the rearhousing sleeve 4. The driven member 40 is pot-shaped, comprising asleeve body open at its rear, formed by a simple circular cylindricalsleeve, projecting backwards from a closed sleeve bottom 41. Said sleevebody is arranged in a surrounding internal sleeve 5 of the rear housingsleeve 4, projecting forward from a rear face of the rear housing sleeve4. The internal sleeve 5 forms a slideway for the driven member 40. Inaddition, it retains the driven member 40 against the force of the driveelement 49 by a number of snap-on elements 6 being evenly distributedover a frontal circumference of the internal sleeve 5 (only one suchelement 6 is visible in the sectional view of FIG. 1) and surrounding afront face of the driven member 40.

FIG. 1 shows the injection device in its base position prior toinjection, in which the driven member 40 is blocked by means of thesnap-on elements 6 and the needle N is surrounded by the needle safetysleeve 10. Due to the needle N being surrounded by the needle safetysleeve 10, the needle is covered for the user of the injection device,in particular when being inserted into the skin, thus reducing apsychological block against inserting the needle N into one's own skin.

For insertion, the needle safety sleeve 10, together with theintermediate sleeve 20 and the releasing sleeve 35, in relation to thehousing sleeves 4 and 7 and the container holder 30 with the container1, can be shifted back against the forward direction (i.e., away fromthe needle). Furthermore, a sleeve-shaped stripper 60 is supported bythe needle safety sleeve 10. Said stripper 60 projects over a front faceof the needle safety sleeve 10 and can be shifted against a restoringelement 69 provided in the needle safety sleeve 10, formed in theembodiment by a restoring spring, into the needle safety sleeve 10. Thestripper 60 serves to strip off a needle safety cap, already removed inFIG. 1. Its removal function will be described with reference to FIGS. 2a and 2 b.

For injecting the product the injection device is positioned on andpressed against the surface of a tissue, generally the human skin. Thispressure initially pushes the stripper 60, forming the front end of theinjection device, against the force of the restoring element 69, intothe needle safety sleeve 10 up to a stop position, in which it iscompletely or almost completely surrounded by the needle safety sleeve10. As soon as the stripper 60 has reached its stop position in theneedle safety sleeve 10, the user releases the blocking means 21 bypressing the releasing button 8, thus releasing blocking againstshifting of the intermediate sleeve 20 in relation to the front housingsleeve 7.

Since the injection device is still pressed against the tissue, theneedle safety sleeve 10, and subject to the pressure exerted by theneedle safety sleeve 10, the intermediate sleeve 20 and therefore thereleasing sleeve 35, are pushed back within the housing. The needle Npenetrates the tissue. Prior to the needle safety sleeve 10 with a rearstop face, formed by an all-round shoulder 12 projecting inwards from arear section of the needle safety slave 10, pushes against the tongues32 of the container holder 30, acting as a stop, the chamfered face 36of the releasing sleeve 35 engages the snap-on elements 6, and releasesthe fixation of the driven member 40 upon the sleeves 10, 20 and 35being driven back further. Release of the fixation occurs at the pointin time when the needle N has reached its desired predeterminedpenetration depth.

At this point in time, the driven member 40 is driven by the drive forceof the drive element 49 in forward direction against a rear face of thepiston rod and drives the piston 2 forward within the container whilebeing driven forward itself. Pushing the piston 2 forward dispenses theproduct from the container through its outlet and the needle connectedto it. In some embodiments, the full content of the container isdispensed upon the drive unit being released. In such embodiments, thecontent of the container is the product dose. In principle, however, bya constructive further development of the injection device, severalselectable product doses could be dispensed during a plurality ofinjections.

During advancement of the driven member 40, the drive force stored inthe drive element is gradually consumed when using a drive spring as adrive element 49, for instance, in accordance with the characteristicsof the spring. The advance speed of the piston 2 would thereforedecrease during the course of advancement and the dispensing rate woulddecrease. In order to compensate for the reduction in drive force whilethe piston 2 is being advanced, a pneumatic damping force acting on thedrive member 40 is generated.

For this purpose, the driven member 40 and the housing, i.e., the rearhousing sleeve 4 form walls of a low-pressure chamber K, the volume ofwhich increases during advancement of the driven member 40. In thisembodiment, the chamber K is formed by the sleeve bottom 41 and thesleeve body of the driven member 40 projecting from the same, and therear face of the rear housing sleeve 4 and the internal sleeve 5projecting from the same. The sleeve body of the drive member 40 and theinternal sleeve 5 are displaced like telescopic sleeves in relation toeach other. In the area of the slideways, i.e., between the externaljacket face of the driven member 40 and the internal jacket face of theinternal sleeve 5, a surrounding seal 42 is arranged. In the embodiment,a washer is placed in a circumferential groove of the sleeve body of thedriven member 40.

Referring to FIG. 1, and FIGS. 1 a and 1 b, the rear face of the rearhousing sleeve 4 comprises a passage “P” into which a seal 50, having acalibrated through-bore “T”, but otherwise being airtight, has beeninserted. Instead of a calibrated through-bore, a one-way or non-returnvalve “V” could be used, allowing the unimpeded escape of air upon thedriven member 40 being driven back, but pressing against a valve seat onaspiration, this leaving only a defined, narrow through-bore, aspredetermined in the design. The volume flow admitted per time unit intothe chamber K is in any case less per time unit than the increase involume of the chamber occurring during the advancement of the drivenmember 40, with a damping force therefore always being generated as longas the driven member 40 is advanced by the resulting drive force. Thefaster the driven member 40 is advanced the larger the generated dampingforce, i.e., the larger the effectively exerted drive force the largerthe damping force generated. The type of damping force generation willtherefore automatically compensate an energy consumption taking place inthe drive unit, since with a decrease of the drive force a decelerationof the driven member 40 and a reduction of the damping force occurs.Simultaneously, other unavoidable or practically unavoidable counterforces are also compensated. Such superficial and other irregularitieswhich cause deceleration or acceleration of the driven member 40, areautomatically accompanied by a change in the volume change work to beperformed by the drive element 49. An exemplary counter force is wallfriction between the container 1 and the piston 2, which is notidentical everywhere over the stroke of the piston 2 within thecontainer 1. In addition, damping is further reduced due to thecompressibility of the medium and the increase in chamber volume duringthe course of advancement of the driven member 40, thus compensatingtwice for energy consumption.

FIGS. 2 a and 2 b show how a needle safety cap 3 may be removed by meansof the stripper 60. FIG. 2 a shows the needle safety cap 3 completelycovering or surrounding the injection needle. This corresponds to thestate of the injection device directly after inserting the container 1and screwing the two housing sleeves 4 and 7 together. At the same time,this represents the transport position of the injection device untiljust prior to injection. For preparation for an injection, the needlesafety cap 3 is initially removed.

FIG. 2 a shows how the removal of the needle safety cap 3 is initiated.For this, initially, the sleeve-shaped stripper 60 is pushed into theneedle safety sleeve 10 against the pressure of the restoring element 69until it presses against the needle safety cap 3 with two diametricallyopposed engaging elements 61. The two engaging elements 61 projectobliquely inwards, like barbs, from the rear interior jacket face of thestripper. When pushing back the stripper 60, the engaging elements 61are more and more strongly pressed against the needle safety cap 3 whichis widened towards the rear.

After firmly clamping the needle safety cap 3 between the engagingelements 61, the stripper 60 may be released. It is returned by therestoring element 69 to its frontal position, as shown in FIG. 2 b,pushing it against a stop shoulder 11 of the needle safety sleeve 10,thus stripping the needle safety cap 3 from the container 1. In thisposition, the needle safety cap 3, which now only loosely covers theneedle N, may be easily and completely removed manually from the front.In order to simplify manual removal, the stripper 60 is provided with atleast two gripping recesses 62.

As the stripper 60 is permanently attached to the injection device, theuser does not have to first tediously introduce it for removal of theneedle safety cap 3. On the other hand, it does not interfere in any wayduring injection. Another advantage resides in the fact that the needlesafety sleeve 10 can be designed completely closed, i.e., without anygripping slot for removal of the needle safety cap 3, thus allowing theneedle N to be completely covered.

FIG. 3 shows an auto-injection device not only for automaticallydispensing the product but also for automatically inserting the needle.Where the same references are used in FIG. 3 as in the embodimentsdescribed above, components of a substantially identical function areidentified. As to the basic mode of operation of the auto-injectiondevice, reference is made to the applicant's parallel German patentapplication No. 198 22 031 and the corresponding U.S. application Ser.No. ______, the disclosures of which are incorporated herein byreference:

In contrast to the embodiment of FIG. 1, damping of the drive forceexerted on the driven member 40 in the auto-injection device of FIG. 3is effected by mechanical friction. This damping frictional force isexerted between a contact pressure element 45, designed as a pliablering, clamped between the sleeve-shaped driven member 40 and a transfermember 46 which is also sleeve-shaped and surrounds the driven member 40during advancement.

In the auto-injection device of FIG. 3, the injection cycle isessentially as follows: a blocking unit blocking the advancement of thedriven member 40 is released by pressing a release tongue 8, and thedriven member 40 is driven forward to the left in FIG. 3, by the driveforce of the drive element 49, which is also a compression spring inthis embodiment. Initially, the contact pressure element 45 forms acoupling between the driven member 40 and the transfer member 46, asshown specifically in detail in FIG. 3 a. The driven member 40 drivesthe transfer member 46 via this coupling The transfer member 46, inturn, advances the container 1, including the needle N attached to thesame at the front end, in relation to the housing.

Thereby, the needle N is pushed forward out of the needle safety sleeve10 a and is inserted. The needle safety sleeve 10 a, in this embodiment,is firmly attached to the housing. Insertion is limited by stopping ofthe container holder 30 at the housing. When stopped, the couplingbetween the driven member 40 and the transfer member 46 is released, asclearly shown in FIG. 3 a. During further advancement, the driven member40 is driven forward in relation to the transfer member 46, pressesagainst the piston rod and advances by it's own further advancement thepiston 2 in the container 1, thus allowing the product to be dispensed.

The contact pressure element 45 is a slotted spring washer similar to apiston ring. This washer is placed in an all-round groove on an externalcircumference of the driven member 40, pressing elastically against theinternal jacket slideway of the transfer member 46. The wall frictionalforce exerted between the impression element 45 and the transfer member46 decreases during the course of advancement of the driven member 40,due to the internal jacket face of the transfer member 46 being widenedin forward direction. This compensates for a decrease of the drive forceof the drive element 49.

A guide ring 47 is placed in a rear section of the transfer member 46,serving as a straight guide for the driven member 40. Said guide ring 47may also be formed as a sealring comprising one or several calibratedthrough-bores or a non-return valve in accordance with the embodiment ofFIG. 1. In this way a pneumatic damping force instead of or in additionto the frictional damping force could be generated. In such anembodiment, the low-pressure chamber would be formed in the gap sectionbetween the transfer member 46 and the driven member 40 being shiftedinto the transfer member 46.

A tensioning handle, projecting through the housing, is used forreturning into rear position and tensioning a holding and release sleeve4 b together with the driven member 40, the holding and release sleeve 4b being displaceably arranged in the housing and jointly connected withthe driven member 40.

FIGS. 4 a-e and 5 a-e, which include elevational, sectional andcross-sectional views, show an auto-injection device in which theadvancement of the container 1 for inserting the needle is effected inthe conventional way by the piston 2, in contrast to the device of FIG.3, i.e. advancement of the container 1 is not decoupled from theadvancement of the piston 2, but is rather effected by the piston 2.However, the injection device of FIGS. 4 a-e and 5 a-e, like that shownin FIG. 1, comprises a needle safety sleeve 10, displaceable in eitherlongitudinal direction in relation to the housing. This displaceableneedle safety sleeve 10 covers the needle after injection, i.e. afterretraction, which is not possible in the auto-injection device depictedin FIG. 3.

In contrast to the embodiment of FIG. 1, however, a stripper 65 isprovided, not permanently connected to the injection device, but whichmust be inserted between the needle safety cap 3 and the needle safetysleeve 10 for removing the needle safety cap 3 until it grips behind theneedle safety cap 3 like a claw, thus allowing removal of the needlesafety cap 3 together with the stripper 65.

FIG. 4 a-e shows an injection device after injection and retraction ofthe needle with the needle safety cap 3 already inserted on it forfuture transport. A special feature of this embodiment is the blockingof the needle safety sleeve 10.

Blocking of the needle safety sleeve 10 securely ensures that the tip ofthe needle cannot freely project, thus eliminating any risk of damage tothe needle N and in particular injury. The needle safety sleeve 10 isblocked by a blocking element 80 relative to the housing in such a wayas to prevent the needle safety sleeve 10 being pushed back againstforward direction.

The blocking element 80 is formed by means of a ring section comprisingtwo engaging elements 81, having the shape of two webs, projecting froman inner jacket face of said ring. As best shown in FIG. 5 a-e on thebottom left-hand side, the needle safety sleeve 10 comprises two slots15 gripped by one each of the engaging elements 81 upon the blockingelement 80 being placed on the housing. The engaging elements 81 thenform stops for those walls of the slots 15 which extend incircumferential direction. The blocking element 80 is obtained bycutting a sleeve open, which sleeve is a circular annular sleeve in theembodiment, wherein cutting open occurs in longitudinal direction andoutside of the central longitudinal axis of the sleeve, so that theblocking element 80 comprises a shell which when seen in cross-section,projects a little over the semicircle. Thus, the blocking element 80 asexplained hereafter with reference to FIG. 4 a-e, is insertable over therear housing sleeve 4 and projects over the largest diameter of the rearhousing sleeve 4 when inserted over it.

As best shown in cross-sections B-B and C-C of FIG. 4 a-e, the blockingelement 80 in carrying out its function as a block is retained on theneedle safety sleeve 10 by means of its snap-in connection. For this theengaging elements 81 are designed flexibly and elastically and providedwith snap-in projections at the front, gripping one of the internal slotedges after passing through each slot 15, thus retaining the blockingelement 80 like a snapper in blocked position, but allowing easy removalwhen required.

FIG. 5 a-e shows the blocking element 80 in its second function, inwhich it blocks the container 1 against advancement. Without thisblocking, during removal of the needle safety cap 3, the container 1would be carried along in forward direction over a certain distanceagainst the force of the elastic restoring element 29 and would snapback into its rear position depicted in FIG. 5 a-e the moment the needlesafety cap 3 is removed, due to the force of the restoring element 49.When snapping back, there would be a risk of damaging the container andan ensuing risk of possibly blocking forward movement of the container 1when inserting the needle N.

In order to prevent this, the blocking element 80 is attached to asection of the housing covering the rear edge of the container 1 whilethe injection device is in its transport position until the needlesafety cap 3 is removed. In this position, as shown in the longitudinalsection of FIG. 5 a-e, the shell body of the blocking element 80 closelysurrounds the housing, as shown in particular in cross-section E-E, andis retained to the rear housing sleeve 4 due to its ends projecting overthe semicircle. The engaging elements 81 do not assume any retentionfunction for the blocking element 80, but now serve as a block for thecontainer 1. For this purpose, the engaging elements 81 grip through thehousing and are positioned in front of an all-round flange provided atthe rear end of the container 1 upon the blocking element 80 beingattached. Since this rear flange of the container 1, extending radiallyoutwards, pushes against the engaging elements 81 of the blockingelement 80 when removing the needle safety cap 3, the container 1 isblocked in rear position and cannot therefore be advanced.

In its position shown in FIG. 5 a-e, the blocking element 80 fulfills athird function, namely to prevent release of the drive unit by blockingthe movement of a release means 70. The release means 70 is then able torelease the driven member 40 from its blocked position when the blockingelement 80 is removed from the housing, thus only allowing advancementof the release means 70 in relation to the housing at this point.

FIG. 6 a-b shows an auto-injection device which corresponds to theinjection device of FIGS. 4 a-e and 5 a-e, except for the release means70 for the driven member 40. A release means 70 a of FIG. 6 a-b, too,consists of a sleeve-shaped body comprising a rear sleeve bottom. Thedriven member 40 is both blocked in its rear position by the releasemeans 70 a and released when operating the release means 70 aaccordingly.

The rear end of the driven member 40 ends in snap means, projectingthrough a rear face wall of the housing and surrounding its rearcircumferential edge, with the snap means of the driven member 40 beingpushed outwards due to their inherent elasticity and retained in theirpositions. As an additional security against unintentionaldisengagement, for instance due to impact, a blocking part 71 of therelease means 70 a, which projects from its sleeve bottom and is formedas a small rectangle when seen in cross section, engages with its longside between two diametrically opposed snap means of the driven member40. In this rotational position, it prevents both snap means bendingtowards each other in the position of the release means 70 a shown inFIG. 6 a-b, which would release the snap-in connection. Furthermore, twocontact pressure members 72 are projecting from the sleeve bottom of therelease means 70 a at a distance from both sides of the blocking part71, which when seen in cross section have the shape of circularsegments. The blocking part 71 projects over the contact pressuremembers 72. The blocking element 80 is initially removed for release ofthe driven member 40, followed by rotating the release means 70 a atleast so far around its longitudinal axis that the snap means of thedriven member 40 can be bent towards each other. During rotation of therelease means 70 a, the contact pressure members 72 are positioned overthe snap means of the driven member 40 when seen in cross section. Whenpushing the release means 70 a towards the driven member 40, theimpression elements 72 push against the snap means of the driven member40, which comprise chamfered rear faces, thus allowing them to bendtowards each other under the pressure of the impression members 72,thereby releasing the snap-in connection of the driven member 40 withthe housing. Due to the pressure exerted by the drive unit 49 the drivenmember 40 is then driven forward.

The blocking element 80 may be designed as a rotary element instead of aplug-in element and could, therefore, remain on the housing afterblocking of the container has been released.

FIGS. 7 a, 7 b and 7 c show the mode of operation of the needleprotection apparatus which prevents the needle N from freely projectingfrom the housing after retraction from the tissue when it could bebroken and/or cause injury if not handled carefully. A feature of theneedle protection apparatus is that the needle safety sleeve 10, whichis displaceable in relation to the housing for the purpose of insertion,is blocked in a needle protection position after retraction of theneedle, so that it can no longer be pushed into the housing. Pushingover the housing externally would also be feasible. The mode ofoperation of the pen for inserting the needle N and dispensing theproduct corresponds to that of the pen shown in FIG. 3.

FIG. 7 a shows the front section of the pen in its base positiondirectly before injection. FIG. 7 b shows the pen in the frontalposition of the container 1, i.e. in injecting position. The needlesafety sleeve 10 has been pushed against the force of the restoringelement 19 into its most rear displacement position in relation to thehousing sleeve 7. The needle N projects out of the housing and theneedle safety sleeve 10 by the desired length.

The needle safety sleeve 10 comprises a rear stop face and a front stopface, limiting the displacement path of the needle safety sleeve 10 inrelation to the front housing sleeve 7 in and against forward direction.When moving the needle safety sleeve 10 in either direction, it passesover a blocking sleeve 80′ provided in the housing and secured againstdisplacement and preferably also rotation, said blocking sleeve 80′comprising at its front end at least one hook 82 which is chamferedoutward obliquely or curved. In an internal jacket section, with whichit slides over the hook 82, the needle safety sleeve 10 comprises awidened section, extending approximately over the length of its maximumdisplacement path, the widened section being preferably a slightlywidened internal diameter. A transitional section 14 extending betweenthe widened section and the adjacent internal cross section ischamfered, thus enabling the needle safety sleeve 10 to slide over thehook 82, subject to the pressure of the restoring element 19, up to apoint behind the transitional area 14. Behind the transitional area 14,in a central section the needle safety sleeve 10 is provided withlongitudinal slots 15, the front faces 16 of which, as best shown inFIG. 7 c, form stop faces each for one of the hooks 82.

The blocking sleeve 80′ ends in a number of elastic and flexible tongues83, evenly distributed over the circumference of the sleeve, the freefront ends of which are each formed as a hook 82. The container holder30 also ends in tongues 33 towards its free front end. When advancingthe container holder 30 against the force of the restoring element 29,these tongues 33 are positioned below the tongues 83 of the blockingsleeve 80′. Each of the tongues 83 is thus supported radially towardsthe inside and can no longer be bent radially inward when the containeris in its frontal position. The tongues 83 are not only supported by thetongues 33 but are in addition pushed radially outwardly. In comparisonwith the tongues 83, the tongues 33 are rigidly formed and may be morerigid than tongues 83.

After retraction of the needle N, the needle safety sleeve 10 is pushedforward again by the restoring element 19. Due to the chamfered face 14and/or the chamfered shape of the at least one hook 82, the needlesafety sleeve 10 is pushed over said hook 82, the end tip of which is,furthermore, elastic and flexible. However, as soon as the needle safetysleeve 10 has been advanced again to a point at which its stop face 16is positioned in front of the hook 82, when seen in forward direction,it is blocked against return by the hook 82 positioned against the stopface 16 in stop position. The hook 82 and the needle safety sleeve 10are in contact with each other by their stop faces which pointvertically to the direction of displacement. In its safety positionshown in FIG. 7 c, the needle N is protected after injection by means ofthe needle safety sleeve 10.

The container holder 30 is therefore simultaneously used as adisplaceable support for the at least one elastic blocking means 82 andfulfills, according to the invention, the dual function of retaining thecontainer 1 and blocking the needle safety sleeve 10. The needle safetyapparatus does not require the auto-injection device to be designedaccording to the invention, although it is used most preferably incombination with the same. It may also be used to advantage in genericauto-injection devices.

The foregoing description of embodiments of the invention has beenpresented for the purpose of illustration and description. It is notintended to be exhaustive or to limit the invention to any precise formdisclosed. The above described embodiments were chosen and described toprovide an illustration of the principles of the invention and itspractical application, and to enable one of ordinary skill in the art toutilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when the claims are interpreted inaccordance with the breadth to which they are fairly, legally, andequitably entitled.

1. (canceled)
 2. The device as set forth in claim 14, further comprisingmeans for generating a damping force, said damping force interactingwith the drive force and counter forces related to use of the device,wherein the damping force decreases in the course of displacement ofsaid piston. 3-4. (canceled)
 5. The device as set forth in claim 14,further comprising means for generating a damping force, said dampingforce interacting with the drive force and counter forces related to useof the device, wherein a contact pressure element is provided forgenerating said damping force, transmitting a clamping force betweensaid driven member and a counter element, wherein one of said drivenmember and said counter element provides a contact pressure surface forsaid contact pressure element, extending in a forward direction of saiddriven member so as to cause the clamping force to decrease in thecourse of advancement.
 6. The device as set forth in claim 5, whereinsaid contact pressure element is a pliable ring, arranged in a gapformed between said driven member and said counter element, said gapwidening in the course of advance of said driven member.
 7. The deviceas set forth in claim 14, wherein a stripper is carried on the device,which stripper can be moved back and forth in a longitudinal directionof the needle in order to strip off a needle safety cap applied to theneedle, said stripper carried on the device in such a way as to allowsaid stripper to remain on the device during an injection and to bepushed back for insertion of said needle.
 8. (canceled)
 9. The device asset forth in claim 14, wherein the device is an auto-injection device,said container, including the needle attached to it, being displaceablein relation to said base section from a base position to anadministering position for insertion of the needle, and, in the baseposition, said container being blocked against advancement by areleaseable engagement of a blocking means.
 10. The device as set forthin claim 9, wherein said blocking means selectively blocks saidcontainer against advancement and said needle safety sleeve againstretraction. 11-13. (canceled)
 14. A device for administering aninjectable product, comprising: a) a base section; b) a containerarranged in the base section from which container a product dose isdispensed through a needle by displacement of a piston associated withthe container; c) a drive unit, comprising a driven member and a driveelement, the drive element applying a drive force on said driven memberupon actuating the drive unit, by which drive force said driven memberis displaced in the direction of the piston, thus advancing said pistonwithin said container; and d) a needle safety sleeve displaceablyarranged in relation to said base section from a base position in whichit generally surrounds the needle to an administering position, in whichsaid needle projects beyond said needle safety sleeve, said needlesafety sleeve being blockable against displacement in a directiontowards the administering position in relation to said base section.